Earth formation surveying device

Details Earth formation surveying device Earth formation surveying device

1999-10-28

2001-06-05

Pezzuto, Robert E. (Department: 3671)

Boring or penetrating the earth

With signaling, indicating, testing or measuring

Providing identifiable indication of core position in situ...

C073S864430

Reexamination Certificate

active

06241029

ABSTRACT:

FIELD OF THE INVENTION
Background of the Invention
The present invention relates to a device for surveying an earth formation. Non-intrusive methods such as seismic surveying are generally applied to identify potential hydrocarbon containing zones in the earth formation. In applying such seismic methods shock waves are generated at the earth surface and the reflections from the various earth layers are detected to provide data on the structure of the various layers. Seismic technology however is limited with respect to spatial and contrast resolution and often seismic surveying is to be supplemented by scouting exploration drilling, while subsequent appraisal drilling is to provide verification for better defined estimates of the volumes of hydrocarbon fluid in place and the recoverable reserves.
In exploration drilling one or more survey tools are lowered into a borehole drilled in the earth formation to provide data on characteristics of the formation. During drilling, drill cuttings (that is the rock particles that are spalled off during drilling) are transported upwardly to surface in a stream of drilling fluid flowing in the annular space between the drill string and the borehole wall. To prevent collapse of the borehole, the borehole is provided with a casing.
Such conventional survey methods are expensive in view of the requirement for casing to be set in the borehole to stabilize the borehole, whereby casing sections are installed in a nested arrangement, with an upper section of relatively large diameter and sections of stepwise decreasing diameter in downward direction.
It is an object of the invention to provide an improved device for surveying an earth formation through borehole formed in the formation, which device obviates the need for casing sections to be set in the borehole.
SUMMARY OF THE INVENTION
In accordance with the invention there is provided a survey device for use in a borehole formed in an earth formation, the device comprising a carrier body carrying earth formation survey means and drilling means arranged at the front end of the device for drilling of the borehole, means for progressing the carrier body through the borehole in correspondence with progress of drilling by the drilling means, and means for removing the rock particles resulting from the drilling process, wherein the means for removing the rock particles comprises means for transporting the rock particles to the rear end of the device and depositing rock particles into the borehole behind the rear end of the device.
By depositing drill cuttings in the borehole behind the device, it is no longer required to transport the cuttings to surface in a stream of drilling fluid. Therefore there is no need to maintain a drilling fluid passage in the borehole, and consequently there is no need to set casing in the borehole. Furthermore, the enormous amount of drill cuttings in the borehole reduces the permeability in the borehole to a sufficiently low level to prevent uncontrolled escape of hydrocarbon fluid to surface (blow-out).
The device according to the invention is intended to target oil or gas in an intelligent way, to provide evidence on the occurrence of oil and gas in prospect formations, and to carry out sophisticated measurements on the earth formation.
To further reduce pressure communication between different layers of the earth formation, and from any such layer to surface, the device suitably comprises means for injecting a borehole sealing compound into the borehole behind the device. Such sealing compound can be, for example, plastic foam or cement.
To obtain information on the position of the device in the formation and to steer the device along a selected route, the device is suitably provided with a gyroscope.
For the sake of completeness, reference is made to U.S. Pat. No. 3,857,289. This publication discloses a telescopic soil sampling device provided at its front end with a drill bit, which soil sampling device is connected with its back end to a drill string for rotating the drill bit.


REFERENCES:
patent: 3584293 (1971-06-01), Iizuka
patent: 3857289 (1974-12-01), Wise et al.
patent: 4345650 (1982-08-01), Wesley
patent: 5377761 (1995-01-01), Kosar et al.

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